Rosati C, Aquilani R, Dharmapuri S, Pallara P, Marusic C, Tavazza R, Bouvier F, Camara B, Giuliano G
Ente per le Nuove tecnologie, l'Energia e l'Ambiente (ENEA), Casaccia Res. Ctr., Biotechnology and Agriculture Division, Via Anguillarese 301, 00060 S. Maria di Galeria (Roma), Italy.
Plant J. 2000 Nov;24(3):413-9. doi: 10.1046/j.1365-313x.2000.00880.x.
Ripe tomato fruits accumulate large amounts of the red linear carotene, lycopene (a dietary antioxidant) and small amounts of its orange cyclisation product, beta-carotene (pro-vitamin A). Lycopene is transformed into beta-carotene by the action of lycopene beta-cyclase (beta-Lcy). We introduced, via Agrobacterium-mediated transformation, DNA constructs aimed at up-regulating (OE construct) or down-regulating (AS construct) the expression of the beta-Lcy gene in a fruit-specific fashion. Three transformants containing the OE construct show a significant increase in fruit beta-carotene content. The fruits from these plants display different colour phenotypes, from orange to orange-red, depending on the lycopene/beta-carotene ratio. Fruits from AS transformants show up to 50% inhibition of beta-Lcy expression, accompanied by a slight increase in lycopene content. Leaf carotenoid composition is unaltered in all transformants. In most transformants, an increase in total carotenoid content is observed with respect to the parental line. This increase occurs in the absence of major variations in the expression of endogenous carotenoid genes.
成熟的番茄果实积累了大量的红色线性胡萝卜素——番茄红素（一种膳食抗氧化剂）和少量其橙色环化产物β-胡萝卜素（维生素A原）。番茄红素通过番茄红素β-环化酶（β-Lcy）的作用转化为β-胡萝卜素。我们通过农杆菌介导的转化，导入了旨在以果实特异性方式上调（OE构建体）或下调（AS构建体）β-Lcy基因表达的DNA构建体。三个含有OE构建体的转化体果实中的β-胡萝卜素含量显著增加。这些植株的果实呈现出不同的颜色表型，从橙色到橙红色，这取决于番茄红素/β-胡萝卜素的比例。AS转化体的果实显示β-Lcy表达受到高达50%的抑制，同时番茄红素含量略有增加。所有转化体叶片中的类胡萝卜素组成均未改变。在大多数转化体中，相对于亲本系，总类胡萝卜素含量有所增加。这种增加发生在内源类胡萝卜素基因表达没有重大变化的情况下。
